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Wednesday, April 24, 2013

Solar Electric - what's missing

The price of solar electric panels has finally (2013) fallen to $1.00US per nominal watt* and even lower.  This is the price which was often quoted as needed to make solar-electric financially viable.  The rate of solar panel uptake has increased but not as much as it should be.  What is missing??

*When a panel is facing directly into the noon day sun, it will produce a certain amount of power.  This is it's nominal wattage and it will be sold as such.  Of course, when the sun hits the panel at a shallower angle or there are clouds, the actual power produced will be less.

First off, let me say that this blog is predicated on the assumption that your government is committed to the premise that the uptake of small renewable generation feeding into the grid is good for the country.  You can take this with a grain or a spoon full of salt depending on which jurisdiction you live in. You will have all sorts of vested interests trying to scupper the uptake of small generation and some governments will be following along like puppy dogs.  However, for the sake of the argument, let's suspend belief and assume that your government has the best interest of the country and her citizens at heart.

What is missing is a defined relationship between the small generator and their power company that is fair to both and punitive to neither.  Short of a revolution in battery technology (and there may be one in the pipe line) it is not worth while for you to go off the grid.  When you generate an excess of power, it will be used by someone else and when you need a top up, the power company will provide it.  The Power company is essentially acting as your battery bank.  A diffuse power generating system has many benefits for the country.  It is almost anti-social and certainly expensive for you to go it alone.    Let's look at some of the considerations we should be concerned about.

Calculation Period
Say, in a hypothetical month, you are producing exactly the same amount of power that you use.  Your power bill for that month should be zero, correct?  Not so fast.  It depends on the calculation period.  Let's assume, further, that during half of the days of the month you produced excess power each day and half of the days you needed a top up.  Let's assume, further, that the power company charges you 20c/kWh* top up and gives you 10c/kWh for your excess**.  If the power company looks at the net top up or excess you used/needed over the month, your monthly bill will be zero.  If however, they do the calculation each day and tot up the result for each day, you will be paying quite a bit.  This argument extends to the seasons.  In summer you will produce more energy than you need; in winter less.  If you have sized your system to more or less meet your needs, if the calculation period is one month, you will be paying quite a bit for the lean months and getting a little for the good months.  If the calculation period is one year, it is of little interest how much you are charged for your net power use or how much you are paid for the excess power you produce.  For the good of the small generator, the longer the calculation period the better. 

*kWh - kilowatt hour - a measure of energy.  The Kilowatt is a measure of power.
** Nothing unfair about this.  It is one, amongst a number of ways to reflect the fact that the power company has to build and maintain the distribution network.

Single vs Double Metering
With single metering many of the problems fall away.  You turn the meter forward when you are using excess energy and turn it back when your generation exceeds your use.  This is often referred to as "net metering"

However with double metering there are a number of possibilities.   The German system is the most insidious.  In Germany you have one meter that measures every kWh you produce and one that measures every kWh you use.  This is not the excess you use above what you are generating or the excess you export above what you are using.  It is every kWh generated or used.  However, a double metering system can be set up so that you use your own generated power instead of the German system (you always thought that this is how it works, didn't you?).  The outgoing meter measures the excess you produce and the incoming meter,measures your top up.

Let's assume your power company is not using the German system so you only draw a top up or export your excess.  You are chugging along, working on your computer, pretty well producing the same amount of power that you are using.  You put the kettle on.  Suddenly you need to suck some power from the grid.  The incoming meter records this and you will be charged for the excess at the company rate.  The kettle finishes  heating your coffee water so you turn off the computer and go for a break.  You are now feeding power into the grid.   You get the reduced rate for the power you produce.  This minute by minute measurement is even worse than a daily calculation period. Your day is micro divided and you are charged for your instantaneous net use and paid for your instantaneous net production* (at the differential rate).  Of course the German system is even worse.  You don't even have the opportunity to use power you produce.

*I just struck me that there may be a fairly easy solution to this problem; the problem being that any instant you are producing excess power your output meter is recording it and any instance that you are using power, your input meter is recording it.  Simply install a modest amount of battery.  Say, for the sake of the argument, two lead acid truck batteries.  Then you just need the electronics to ensure that you access the power in these batteries before drawing from the grid and that your power goes first into these batteries before you export to the grid.  This would probably give you a couple of hours of buffering.

Now we come to taxation.  Do you remember that at the outset, I said we will pretend that your government recognizes the benefit of small diffuse generation and will face down all the vested interests (wouldn't that be nice for a change).  With the German system in which every kWh you produce and every kWh you use is measured or with the somewhat more benign system where your meters only measure your excess or your top up, you will pay income tax at your marginal rate for any revenue you receive and will pay GST (VAT) for every kWh you buy. If the government truly wants diffuse generation with all it's benefits, they should restrain themselves from taxing the system.  Taxation has two functions.  One is to collect revenue so that the government can do her good works.  The other is to direct the path of society.  It is hardly directing us to increase our uptake of solar technology by trying to milk the calf before it is even a cow.

Of course, the power company could say that they will simply subtract the excess power you use from the excess power you produce and charge or pay you, depending on whether your balance is positive or negative.  The government will then charge you GST if you buy some net electricity or charge you income tax if you earn some money from your excess.  If this is what they intend, why then bother with the expense of a second meter.  Far simpler to put in one meter which turns backwards when you are producing excess power.  If the power company and the government does try to peddle this line, watch out.  Suppose they say "we will have double metering but you will be charged or paid depending on the difference between these two amounts".  They are thinking ahead and hoping you are not.  At any time in the future they can decide to change the rules.  If you are double metered, they have you by the short and curlies.  But.......You have probably spotted the problem with single metering.

With single metering, the power company is essentially paying you the same for the power you produce and power you use  (except for any excess or deficit but that is another story).  The solution is simple.  There must be a line charge which reflects the fact that they must build and maintain the lines.  However, we come to another fish hook.  The power company will be tempted to  charge the simple user a larger price for their power and a very small line charge.  They don't need a line charge if they are getting a good price for the power they sell you.

For the small generator, however, they will charge a very small charge for electricity (and hence you will get very little for the power you produce) but you will pay a large line charge.  The solution is simple.  It must be legislated that the price per kWh and the line charge are the same for both types of customers.  The power company will work out the formula that optimizes their profits but will not be able to shaft either type of customer.  Incidentally, when there are few customers generating power, they will focus their attention on the simple user and this will be very good for the small generator.  This is great since it will greatly encourage the uptake of solar electricity at this early stage.  As more and more of us are generating our own power, the formula will change.

I have only touched on a couple of consideration to think about when structuring the relationship between the power company and the small generator/user.  Very little is the way it seems at first glance.  For Instance, in Germany, they give you three times the rate for the power you produce   than for the power you buy.  Are you ever suspicious when something seems too good to be true.  Most power users don't look any deeper.  The German system is far less  beneficial to the customer than it appears to be at first glance and increases the cost of power to all consumers.

Saturday, April 13, 2013

Why aren't conservatives conservationist

I just don't get the right wing of various countries and especially those in the US of A.  By and large, the Republicans and their nutty fringe, the Tea Party, seem to contain a huge proportion of religious fundamentalists.  By contrast, the Democrats, the left wing, seem rather rich in atheists and agnostics.  I mean, can you imagine someone like Bill Maher in the US or Richard Dawkins in the UK belonging to the right wing.  Not on your Nelly.

In the good book that the Religious right constantly harks back to* god gave us dominion over the beasts in the fields, the birds in the Air and the fish in the sea**.  Dad was passing on the family business to us.  He didn't specifically say, "take care of it" but I think we would be justified in assuming that was his intention. 

*Senator Joe Barton of Texas just tried to deny climate change by saying that the biblical flood was an indication of climate change before there was any significant increase in CO2.  Jeeessssh!!

**Read Farley Mowat's book, Sea of Slaughter.

Why is it then that by and large,  the religious right that wants to drill, mine, log fish, and exploit the environment with no thought for the future while the agnostic left wants to preserve gods bounty.

I just don't get it.  Why aren't conservatives conservationists.

Monday, April 8, 2013

The Beaufort Gyre

The Beaufort Gyre is a clockwise rotating ocean current situated in the Arctic Ocean  north of Alaska (on the Bearing Strait side). This gyre has some interesting connections with climate change.  Let's go back a few steps and trace the cause/effect chain.

In times when the Arctic Ocean is largely covered with ice, most of the radiant energy from the sun is reflected back out into space.  The air above the Arctic also radiates energy into space*.   The air becomes cold, dense and sinks.  When it approaches the surface of the earth it spreads out southward across the Tundra.

*Any material which is above 00 Kelvin {minus 273 centigrade} radiates energy

Coriolis gives the south flowing air a bend to the right so we have North East winds (flowing toward the south west).  In other words this results in a clockwise rotating weather system.  The wind pushes on the water and ice and causes the clockwise rotating Beaufort Gyre.  Now something interesting happens.

You would expect that with a rotating gyre, water would be flung outward resulting in a slightly lower water level in the middle.  Think of those rotating mercury filled dishes which form perfect mirrors for studying the stars.  However, something peculiar happens with the Gyre.  The middle has been observed to  be a little higher than the surrounding water*.  Coriolis is once more the answer.

* This probably explains the accumulation of Sargasso weed and plastic in the middle of the world's other oceanic gyres.

The water which is being pushed clockwise around the gyre is also bent to the right.  In a clockwise rotating current, 'right' is into the centre.  Since the surface water of the Arctic Ocean is fresher than the warmer saltier deeper water, this bulge is of fresher water.  The fresh water comes from rivers and melting ice and the halocline is about 200m deep on average.  The Beaufort Gyre Exploration Project reports that the amount of fresh water stored on the surface of the Arctic Ocean is equal to a number of years flow of rivers emptying into the Arctic ocean.  However, the Beauford Gyre can reverse direction.  As reported by the BGEP, the cycle is from 4 to 8 years in each direction.

All it takes is a low pressure area over the Arctic with rising air causing surface air to be sucked in from the surrounding area.  With a bend to the right, this will result in a counter clockwise rotating weather system and if it is strong enough and persists for long enough, it will result in a counter clockwise rotating Beauford gyre.  Such a situation is likely to happen with increased frequency as the Arctic Ocean becomes more and more ice free and open water absorbs the radiant energy that used to be reflected back into space.  This will cause an ocean which is warmer than the surrounding air and lead to rising air and off-shore winds.

With a counter clockwise rotating body of water in the Northern Hemisphere, a bend to the right is away from the centre.  This layer of fresher surface water along with any floating ice trapped in the gyre, will be moved away from the centre of the gyre, resulting in lower water in the centre.  This may be exacerbated by the "liquid mirror" effect.  If strong enough, this should result in upwelling of the deep, warmer, saltier water which underlies the surface water.  The normal (historical) clockwise rotating Beaufort Gyre keeps fresher surface water and floating ice in the Arctic and helps the production of multi year ice by keeping the ice in the Arctic Ocean.  Fresher water also freezes more easily.  A counter clockwise Beaufort Gyre pushes surface water and ice into the trans-polar drift and out of the Arctic.

A related effect will be the freshening of the North Atlantic surface water and if great enough could shut down or weaken the Gulf Steam*. When would we be likely to see a reversed Beaufort Gyre?

* As odd as it seems, this could result in a year or two with winter temperatures on the West coast of Europe similar to those on the East Coast of North America at the same latitude.

It could be that it already has happened.  If you look at the October 2012 edition of the NSIDC report, they already report rising air over the Arctic ocean with winds from the south.  It makes sense that fall would be when we would first see this situation.  The land is cooling rapidly as the sun leaves the north while the sea has an accumulation of heat from the summer.  Offshore (southern) winds,  with Coriolis, will  cause a  counter clockwise rotating weather system which in turn will reverse the direction of the Gyre.  As mentioned, such a system will also fling floating ice and surfac fresher water outward, possibly to be caught by the Transpolar Current and expelled from the Arctic through Fram Strait.  Whether this 2012 reversal of the air circulation was strong enough or lasted for long enough to reverse the Beaufort Gyre is unclear.

There is enough heat in the deeper Atlantic water to melt all the surface ice about three times over.  This looks to be another of these much anticipated tipping points. Warmed surface water gives rise to a counter clockwise Beauford gyre which in turn expels surface fresher water from the Arctic and brings up deep salty warmer water to melt more ice which leads to more warming as more of the surface of the ocean becomes open water.

 A thinner surface layer of fresher water is also easier to disrupt  than the present thicker layer.  The disappearance of the Arctic ice  would then accelerates far faster than would be expected from considerations of climate sensitivity or thermodynamics.

There is another little wrinkle in this scenario.  If you look at wave dynamics, the circle of rotation of a particle in a wave, halves for every ninth of a wave length you go down into the water*.  So the mixing effect of short waves on layers of water decreases rather quickly.  The effect of longer waves penetrates deeper than short waves.  With a shallower layer of fresher water and the huge waves caused by hurricanes, mixing can be much more effective*.  It seems likely that at some point as the fresher layer thins and storms increase, we will see a relatively sudden (over a few years) warming and increase in salinity of Arctic surface waters*.

*As the ice thins, much larger, longer waves can be anticipated.

The internal waves between layers of water of different density is something else again.  The height of a wave is inversely proportional to the density difference between the layers.   The density difference between adjacent layers of water is small so the waves are large.  They also break as they reach shallow water just as water/air waves do, mixing the layers.

*Suppose you have a wave which is 18m from peak to peak and the wave is 1m high.  On the surface, a particle is describing a 1m circle as the wave goes by.  At a depth of two meters (1/9th of a wave length), a particle is describing a 50cm circle.  By the time you get to 10 meters, the circle of rotation is only 3cm.  The higher and longer the wave, the deeper the effect is felt.  The mixing due to such waves is particularly strong when the waves move into shallow water and break.  The break is not only on the surface between water and air but also between layers of water of different densities.  Wave height is inversely proportional to the density difference between the two media in contact where the wave occurs.

Of course we then get to the possibility of really large waves; of land slumps under water.  As methane evolves out of the bottom of the Arctic ocean, the Clathrate which is at present holding the sediment together melts.  A small tremor can then induce a land slide, causing localized but rater intense tsunamis.  As these bounce back and forth across the Arctic, some severe mixing is likely

Quite exciting if you are in to horror movies.